1. Field of Invention
The present invention relates to the manufacture of solid materials such as gypsum wallboard having cut fibers disposed therein, and more particularly refers to a novel device for monitoring a cutting apparatus which cuts long fiber roving strands into short clippings, the monitoring device being arranged to actuate an alarm and to turn off the cutting apparatus when it malfunctions.
2. Description of the Prior Art
Gypsum wallboard is conventionally made with short cut fibers dispersed therein when it is desired to enhance the mechanical properties of the board.
In practice, long roving strands of glass fiber are introduced into a conventional cutter which cuts the strands into short strands or clippings. The short strands are then introduced into a mixing chamber and mixed with a gypsum slurry and the slurry conveyed out of the chamber and spread onto a belt in a thin sheet having paper cover sheets on both bottom and top surfaces. After extended operation the blades of the cutter become dull and fail to cut the long rovings. The long uncut rovings are as a result introduced into the mixing chamber and screw conveyer where they cause extensive tangling of the conveyor blades and eventually cause the apparatus to malfunction and to stop. Generally several hours of shut-down time are required in order to clean out the entangled apparatus. Such a shut-down is very expensive and requires skilled labor to restore the apparatus to normal operation again.